Is Britney Spears in an Abusive Relationship?

Britney Spears has been happily dating Jason Trawick for over a year but is their relationship toxic?

The pop star's rep is denying a new tabloid report, which claims that Trawick has been physically abusive toward Spears.

The allegations were made by Spears's one-time husband, Jason Alexander, whose 55-hour Las Vegas marriage to the singer was annulled in 2004. In the tabloid report, Alexander says Spears told him Trawick "beat on me."

An audio clip of the alleged conversation was posted on RadarOnline Wednesday, but the singer's manager Larry Rudolph denies that the female voice belongs to Spears, who turns 29 on Thursday.

It is "100 percent not her," Rudolph told Access Hollywood. "Lawyers are amassing. We are 100 percent taking stern and immediate legal action."

Sources close to the couple also tell PEOPLE that allegations of violence are untrue.

"Jason has never been abusive to Britney," says one close source. "Britney has in the past been very difficult and has had tantrums around Jason, but he was and is nothing but patient with her."

In fact, says the source, "The couple’s relationship is better [than ever]. Britney and Jason lately have been very happy together."